The defective sensibility of the degenerate, confirmed by all observers, is, moreover, susceptible of different interpretations. Whereas many consider it a consequence of the pathological condition of the sensory nerves, others believe that the perturbation has its seat, not in these nerves, but in the brain; not in the ducts, but in the centres of perception. To quote one of the most eminent among the psycho-physiologists of the new school, Binet[245] has proved that, ‘if a portion of the body of a person is insensible, he is ignorant of what passes there; but, on the other hand, the nervous centres in connection with this insensible region can continue to act; the result is that certain acts, often simple, but sometimes very complicated, can be accomplished in the body of a hysterical subject, without his knowledge; much more, these acts can be of a psychical nature, and manifest an intelligence which will be distinct from that of the subject, and will constitute a second “I” co-existent with the first. For a long time there was a misconception of the true nature of hysterical anæsthesia, and it was compared to a common anæsthesia from organic causes, due, for example, to the interruption of afferent nerves. This view must be wholly abandoned, and we know now that hysterical anæsthesia is not a true insensibility; it is insensibility from unconsciousness from mental disaggregation; in a word, it is psychical insensibility.’ Most frequently it is not a question of simple cases, where it is the sensory nerves alone, or only the cerebral centres which work badly, but of mixed cases, where the two apparatuses have a diversely varying part in the disturbance. But whether the nerves do not conduct the impressions to the brain, or the brain does not perceive, or does not raise the impressions brought to it into consciousness, the result is always the same, viz., the external world will not be correctly and distinctly grasped by consciousness, the ‘not-I’ will not be suitably represented in consciousness, the ‘I’ will not experience the necessary derivation of the exclusive preoccupation with the processes taking place in its own organism.